system for supplying fuel from a tank (2) to a manifold (5) that distributes fuel into an engine (3); the system (1) having a pumping unit which connects together the tank (2) and the manifold (5) and has a fluid line (11) with a first or low-pressure portion (P1), a second or high-pressure portion (P2), a high-pressure pump (9) connecting together the first and second portions (P1, P2); the first portion (P1) having a plurality of low-pressure branches (23-28, 30-34), a plurality of fluid components (8, 13, 21, 29, 231, 232, 233, 241, 242, 251, 261, 271, 311), each of which has at least one connector (36) and at least one tubular coupling (40; 140; 340; 440), which latter is inserted partly into the connector (36) and partly into a low-pressure branch (23-28; 30-34); each coupling (40; 140; 340; 440) having a plastic tubular body (145; 345; 445).
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11. A coupling for connecting a fluid component (8; 13; 21; 29; 231; 232; 233; 241; 242; 251; 261; 271; 311) to a low-pressure branch (23-28, 30-34) of a fuel supply system (1) of an internal-combustion engine (3), the fluid component (8; 13; 21; 29; 231; 232; 233; 241; 242; 251; 261; 271; 311) having a connector (36), the coupling (40; 140; 340; 440) comprising:
a plastic tubular body (145; 345; 445);
a sealing arrangement (41; 141; 341; 441) interposed between the tubular body (145; 345; 445) and the connector (36); and
an axial locking arrangement (42; 142; 342; 453) for axial locking of the tubular body (145; 345; 445) with respect to the connector (36) in a defined axial position, each coupling (40; 140; 340; 440) comprising an axial stop arrangement (44; 144; 351; 453) for the tubular body (145; 345; 445) with respect to its connector (36) in said defined axial position, the connector (36) having an end surface (38) and a cylindrical housing (39) which begins at the end surface (38) and houses part of its coupling (40; 140; 340; 440), the sealing arrangement (41; 141; 341; 441) and the axial locking arrangement (42; 142; 342; 453), the cylindrical housing (39) having an annular groove (45), the axial locking arrangement (42; 142; 342; 453) being a snap-action arrangement (453) engaging with said groove (45) and being made in one piece with the tubular body (445).
16. A fuel supply system for an internal-combustion engine (3) in which the system (1) comprises a fuel supply tank (2), a fuel distribution manifold (5), and a pumping unit (6) which connects together the fuel supply tank (2) and the fuel distribution manifold (5); the pumping unit (6) comprising a fluid line (11) having a first, low-pressure portion (P1), a second, high-pressure portion (P2), a high-pressure pump (9) connecting together the first and second portions (P1, P2), and a pre-supply pump (8) connected to the first portion (P1); and the first portion (P1) comprising a plurality of low-pressure branches (23-28, 30-34), a plurality of fluid components (8, 13, 21, 29, 231, 232, 233, 241, 242, 251, 261, 271, 311), each of which has at least one connector (36) and at least one tubular coupling (40; 140; 340; 440), which tubular coupling is inserted partly into the connector (36) and partly into one of said low-pressure branches (23-28; 30-34) to connect together the component (8; 13; 21; 29; 231; 232; 233; 241; 242; 251; 261; 271; 311) and the low-pressure branch (23-28; 30-34); the system (1) being characterized in that each coupling (40; 140; 340; 440) comprises a plastic tubular body (145; 345; 445), sealing means (41; 141; 341; 441) interposed between the tubular body (145; 345; 445) and the corresponding connector (36), and means (42; 142; 342; 442) for axial locking of the tubular body (145; 345; 445) with respect to its connector (36) in a defined axial position, in which the axial locking means (442) are snap-action locking means (453) that include an annulus of elastically deformable teeth (453) projecting radially outwards from the tubular body (445).
1. A fuel supply system for an internal-combustion engine (3) in which the system (1) comprises a fuel supply tank (2), a fuel distribution manifold (5), and a pumping unit (6) which connects together the fuel supply tank (2) and the fuel distribution manifold (5); the pumping unit (6) comprising a fluid line (11) having a first, low-pressure portion (P1), a second, high-pressure portion (P2), a high-pressure pump (9) connecting together the first and second portions (P1, P2), and a pre-supply pump (8) connected to the first portion (P1); and the first portion (P1) comprising a plurality of low-pressure branches (23-28, 30-34), a plurality of fluid components (8, 13, 21, 29, 231, 232, 233, 241, 242, 251, 261, 271, 311), each of which has at least one connector (36) and at least one tubular coupling (40; 140; 340; 440), which tubular coupling is inserted partly into the connector (36) and partly into one of said low-pressure branches (23-28; 30-34) to connect together the component (8; 13; 21; 29; 231; 232; 233; 241; 242; 251; 261; 271; 311) and the low-pressure branch (23-28; 30-34); the system (1) being characterized in that each coupling (40; 140; 340; 440) comprises a plastic tubular body (145; 345; 445), sealing means (41; 141; 341; 441) interposed between the tubular body (145; 345; 445) and the corresponding connector (36), and means (42; 142; 342; 453) for axial locking of the tubular body (145; 345; 445) with respect to its connector (36) in a defined axial position, each coupling (40; 140; 340; 440) comprising axial stop means (44; 144; 351; 451) for the tubular body (145; 345; 445) with respect to its connector (36) in said defined axial position, the connector (36) having an end surface (38) and a cylindrical housing (39) which begins at the end surface (38) and houses part of its coupling (40; 140;340; 440), the sealing means (41; 141; 341; 441) and the locking means (42; 142; 342; 453), the cylindrical housing (39) having an annular groove (45), the axial locking means (42; 142; 342; 453) being snap-action locking means (453) engaging with said groove (45) and being made in one piece with the tubular body (445).
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The present invention relates to a fuel supply system for an internal-combustion engine, especially for supplying diesel to an endothermic diesel-cycle engine installed in a motor vehicle.
A system of the type described above generally comprises, in the prior art, a fuel supply tank (at low pressure) and a fuel distribution manifold (at high pressure), from which the fuel is fed into the engine through a plurality of injectors.
The fuel supply tank and the distribution manifold are connected to each other by a pumping unit in which a fluid line comprises a low-pressure portion and a high-pressure portion. These portions are connected by a high-pressure pump. The low-pressure portion comprises a pre-feed pump mounted in series with the high-pressure pump on the aforementioned fluid line.
The low-pressure portion also includes a plurality of low-pressure branches and a plurality of fluid-line components, each of which is connected to at least one low-pressure branch by a connector provided with a coupling inserted partly into the connector and partly into the low-pressure branch.
The couplings mentioned above are usually made of metal and are fixed inside their connectors by screwing or pressure; in this second case the couplings are usually made of brass.
A system such as that described above has the drawback that the metal couplings are heavy and, in the case of screw couplings, the couplings and their connectors require expensive machining by chip removal.
In the case of brass couplings there is the drawback that Zn and Cu ions from the coupling itself dissolve into the fuel causing both internal abrasion of the pumping unit and deposition, inside the injectors, of hard sediments, which reduce the flow rate and uniformity of the distribution of the fuel entering the engine.
It is an object of the present invention to provide an internal-combustion engine fuel supply system capable of eliminating the drawbacks described above.
The invention will now be described with reference to the appended drawings, which show certain non-restrictive examples of embodiments thereof, in which:
In
The engine 3 comprises fuel supply injectors 4 downstream of a manifold 5 defined by a container usually called the “common rail”, which distributes the fuel. The manifold 5 is designed to contain the fuel at a pressure preferably, but not necessarily, greater than 2000 bar.
The system 1 comprises a pumping unit 6 for pumping the fuel from the tank 2 to the manifold 5, and a control device 7 for regulating the flow of fuel through the system 1 on the basis of the demand of the engine 3 for fuel, instant by instant.
In turn, the pumping unit 6 comprises a pre-supply pump 8, preferably a gear pump, and a high-pressure pump 9, preferably a positive-displacement piston pump 10. These pumps are arranged in series on a fluid line 11 that connects the tank 2 to the manifold 5 via the pumping unit 6.
The high-pressure pump 9 comprises a pump casing 12 containing a volume 13, preferably of circular section, for the partial housing of a drive mechanism 14 for the pistons 10 which, as will be explained later in more detail, are connected to the drive mechanism 14. Inside the volume 13 are opposing cavities 15, each containing the axially sliding fluid-tight free end of a respective piston 10. Generally speaking, both the pistons 10 and the cavities 15 are of circular section.
The drive mechanism 14 comprises a shaft 16 mounted so as to be rotatable about an axis 17 and comprises an eccentric portion 18 on which a polygonal ring 19 is mounted so as to rotate freely.
The shaft 16 is mounted rotatably inside the pump casing 12 on support bearings or brasses (not shown), of known type, arranged on opposite sides of the volume 13. The mounting of the shaft 16 inside the pump casing 12 is of known type and also includes seals of known type (not shown) to prevent fuel leaking out of the pump casing 12. A shaft 16 is furthermore connected, in a manner known per se and not shown, to the output drive shaft of the engine 3 and, in a preferred embodiment (not shown), is also connected to the pre-supply pump 8, which is powered by the shaft 16 together with the high-pressure pump 9.
Each piston 10 has a sliding connection, via a respective intermediate element or slider 20, to a respective peripheral planar surface of the polygonal ring 19, which when in use rotates translationally about the shaft 16. The sliding of its slider 20 against its corresponding peripheral planar surface means that the rotation of the shaft 16 about its axis 17 corresponds to a reciprocal axial movement of each piston 10 in its own radial direction with respect to the axis 17 along its particular cavity 15.
The pistons 10, of which there are three in the example illustrated, although there could be a different number of pistons, are distributed at equal intervals around the axis 17.
Each cavity 15 communicates with the fluid line 11 through a supply valve 21 and a delivery valve 22, which are built into the pump casing 12 and are of known type.
The fluid line 11 comprises a low-pressure portion P1 and a high-pressure portion P2.
In more detail, the low-pressure portion P1 comprises:
The high-pressure portion P2 comprises:
In a preferred embodiment (not shown), the pre-supply pump 8 and the high-pressure pump 9 are inserted into a common pump casing, in which the branches of the fluid line 11 are made by removal of material.
Along the low-pressure portion P1 are a plurality of attachment devices A for connecting the fluid components described above to the low-pressure branches.
Each attachment device A comprises a connector 36 formed on a corresponding fluid component and comprising a cylindrical body 37 having a free end surface 38 and a longitudinal cylindrical housing 39 formed axially inside the body 37 and extending from the free end surface 38.
Each attachment device A also comprises a coupling 40 inserted partly into the connector 36 and partly into a low-pressure branch 23-28 and 30-34. Each coupling 40 comprises at least one seal 41 (only one seal 41 is shown in the example illustrated, but two or more seals 41 can also be used in succession, in examples which are not illustrated) and at least one connecting element 42 inserted into the cylindrical housing 39 of the corresponding connector 36 in an axial position defined by its contact with a generally annular shoulder 43 on its own stop element 44 with the free end surface 38 of the body 37 of the connector 36.
The tubular body 145 has a longitudinal axis 146 and two axial openings marked 147, 148, each formed at a corresponding free end of the tubular body 145. The axial openings 147 and 148 allow communication between the exterior and a longitudinal cylindrical internal cavity 149 of the tubular body 145 and define the ports through which the coupling 140 allows intercommunication between the components of the low-pressure portion P1 of the fluid line 11.
As shown in
The tubular body 145 has an external annular groove 150 which is next to the axial aperture 147 and houses the seal 141, which is of known type and of toroidal shape. The tubular body 145 also has an external annular flange 151 in an intermediate part of the tubular body 145, particularly a part where the diameter of the cavity 149 varies; and an annular groove 152 which is between the groove 150 and the flange 151 and houses the connecting element 142.
In the embodiment shown in
The flange 144 defines, on the coupling 140, the stop element 44 of the generic coupling 40; while the seal 141 and the connecting element 142 corresponds to the seal 41 and to the connecting element 42, respectively, of the generic coupling 40.
The seal 141 and the connecting element 142 are an interference fit between the housing 39 of the connector 36 and the tubular body 145 of the coupling 140.
The tubular body 345 has a longitudinal axis 346 and two axial apertures 347 and 348, each of which is made at a respective free end of the tubular body 345. The axial apertures 347 and 348 lead into an internal cavity 349 of cylindrical shape and define the ports through which the coupling 340 allows intercommunication between the components of the low-pressure portion P1 of the fluid line 11.
The tubular body 345 has an external annular groove 350 which is next to the axial aperture 347 and houses the seal 341, which is of known type and of essentially toroidal shape; an enlarged external annular portion 351 located in an intermediate part of the tubular body 345 and having a plurality of external annular grooves, especially two; an annular groove 352 interposed between the groove 350 and the enlarged portion 351 and housing, as will be explained in more detail later, an external peripheral portion of the connecting element 342; and a flange 353 between the enlarged portion 351 and the axial aperture 348.
As illustrated in
The enlarged portion 351 defines on the coupling 340 the stop element 44 of the generic coupling 40; while the seal 341 and the connecting element 342 correspond to the seal 41 and the connecting element 42, respectively, of a generic coupling 40.
The seal 341 and the connecting element 342 are an interference fit between the housing 39 of the connector 36 and the tubular body 345. The coupling 340 is preferably fitted to connectors 36 made of aluminium.
The tubular body 445 has a longitudinal axis 446 and two axial apertures marked 447 and 448 at a free end of the tubular body 445; the axial apertures 447 and 448 lead into a cylindrical internal cavity 449 and define the ports through which the coupling 440 allows communication between the components of the low-pressure portion P1 of the fluid line 11. The tubular body 445 has an annular external groove 450 which is next to the axial aperture 447 and houses the seal 441, which is of a known type and essentially toroidal; an enlarged annular portion 451, which is in an intermediate portion of the tubular body 445 and has a plurality of annular grooves, in particular two mutually parallel annular grooves; and a flange 452 between the enlarged portion 451 and the axial aperture 448.
The connecting element 442 is made integrally on the tubular body 445, projects (
The enlarged portion 451 defines on the coupling 440 the stop element 44 of the generic coupling 40; while the seal 441 and the connecting element 442 correspond to the seal 41 and the connecting element 42, respectively, of a generic coupling 40.
The connecting element 442 engages by snap action with the groove 45.
Attachment devices A are preferably arranged at the inlet of the pre-supply pump 8 and on the connectors 36 of the collecting branch 30. In the latter case the use of an attachment device A is strongly advised because fuel returning to the tank 2 is hot and will encourage chemical processes in the tank 2 caused by the presence of Zn and Cu ions which will cause deterioration to the quality of the fuel.
The tubular body 145, 345 and 445 may be straight, or it may be L-shaped (
The couplings 40, 140, 340 and 440 are inserted, as described earlier, with one end into a respective connector 36 and the other end into a respective low-pressure branch 23-28, 30-34. The shape and size of the tubular body 145, 345 or 445 are decided on the basis of the shape and size of the corresponding low-pressure branch into which it is inserted.
It is stressed that the coupling 140 or 340 is fixed inside the coupling 36 by interference with the housing 39, and the corresponding connecting element 142 or 342 is of metallic material; while the coupling 440, which comprises a plastic connecting element 442, is fixed to the connector 36 by snap action.
The 140 type of coupling 40 is preferably used instead of known pressure couplings 40, which usually have an all-brass body, while the 340 and 440 type of couplings 40 are mostly used instead of screw couplings, which usually have threaded steel bodies.
It is important to stress that the couplings 140, 340 and 440 can be connected by simply inserting them into a corresponding connector 36, reducing assembly times and costs.
It follows from the above account that the couplings 140, 340 and 440 are lighter and cheaper than corresponding known couplings; and, because of their plastic tubular body 145, 345 or 445, they prevent contact of the fuel with metallic components, especially brass components, which contain alloys of Zn and Cu.
The L-shaped tubular body 145, 345 or 445 allows connections to be made between mutually transverse components, avoiding the use of known Banjo type couplings, which are usually made of metal and are expensive to manufacture.
Ziegler, Thomas, Motolese, Giuseppe
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jul 02 2010 | Robert Bosch GmbH | (assignment on the face of the patent) | / | |||
Jan 16 2012 | MOTOLESE, GIUSEPPE | Robert Bosch GmbH | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 027707 | /0564 | |
Jan 24 2012 | ZIEGLER, THOMAS | Robert Bosch GmbH | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 027707 | /0564 |
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